The invention relates generally to embossing foils and more particulary to hot embossing foils.
U.S. Pat. No. 4 376 006 discloses an embossing foil construction comprising a backing foil and a transfer layer which can be released therefrom and which comprises at least a magnetic layer consisting of a dispersion of magnetisable particles in a binding agent. A metal layer and a layer of lacquer are provided on the side of the magnetic layer which is towards the backing foil, while the magnetic layer is possibly provided with an adhesive layer, on the side thereof which is remote from the backing foil, for fixing the transfer layer to a substrate to which it is to be applied. That design seeks to afford the possibility of the magnetic embossing foil also being produced in bright, attractive colours, for which purpose the magnetic layer, which is generally dark, is covered by the metal layer. Purely decorative purposes are therefore the consideration in that respect.
It is conventional practice for for example cheque cards, credit cards, savings books and similar security documents and items to be provided with magnetic strips, strips which can be signed thereon or structures which have a particular optical effect in order thereby to make it possible to store certain items of data or to enhance the safeguards against forgery. An advantage when using magnetic strips is that it is very easily possible to provide for suitable storage of relevant data in the magnetic strip. However, there is the disadvantage that forgery or erasure is a comparatively simple manner with the usual forms of magnetic strips. In principle that depends on the way in which the magnetic strip is applied. It is true to say that for many areas of use, it has been found to be advantageous for the magnetic strips to be applied by means of embossing foils such as hot-process embossing foils because in that case the strip can be easily applied to the security document or like item, and it is even possible for the magnetic strip to be coded before being applied to the document or card in question.
Some forms of security documents or items, for example credit cards and cheque cards, additionally include an area or panel for bearing a signature thereon, with the card being valid only after having been signed in the appropriate area. Signature areas of that kind are already being produced using embossing foils, in which connection the attempt has already been made to improve the safeguards in regard to forgery of the card by virtue of the signature areas having a background of a specific nature, for example by means of a suitable imprint, by using a background material which changes in colour when an attempt at erasure is made or which reacts with the writing liquid to undergo a change in colour, and so forth. In the past however the signature surfaces were always produced in a separate working operation at a location which was provided only specifically for that purpose, as it was assumed that the signature had to be at a location which was not used for other purposes. Any magnetic strips on the same card were always disposed completely separate from the area which was intended to bear the signature of the card holder.